Dementia is a highly prevalent problem causing considerable disability and even mortality. Among the most common forms of dementia are the three degenerative forms Alzheimer's disease (AD), dementia with Lewy bodies (also known as Lewy-Body Dementia (DLB)), and Frontotemporal Dementia (FTD).
Various lines of research, including clinical, pathological, and genetic analysis indicate that the degenerative forms of dementia have different underlying etiologies and pathogenetic mechanisms.
Given the presumably different mechanisms underlying the aforementioned types of dementia, future therapies will probably differ for each major form of degenerative dementia. The ability to differentially diagnose between Alzheimer's disease, Lewy-Body Dementia, and Frontotemporal Dementia will be a major advantage not only for the individual patient being treated, but also with respect to the economic strains of public health systems. However, at present, precise differentiation of Alzheimer's disease, Lewy-Body Dementia, and Frontotemporal Dementia is only possible by post-mortem analysis of brain tissue.
Despite the lack of specific therapeutic regimens for the aforementioned different types of degenerative dementia, pre-mortem diagnosis is already an issue today, as an accurate diagnosis will have clinical utility. For example, precise diagnosis is important when counseling patients and families about prognosis and the question of whether e.g. cholinesterase inhibitor therapy should be undertaken, given that it is not considered to be effective for Frontotemporal Dementia. Patients suffering from Lewy-body Dementia are susceptible to neuroleptic agents.
At present, positron emission tomography (PET) and single photon emission computer tomography (SPECT) are used to undertake pre-mortem analysis of patients suspected of suffering from dementia.
In the past, FDG-PET and perfusion SPECT have been shown to discriminate patients suffering from Alzheimer's disease from normal controls, while allowing some degree of differential diagnosis between Alzheimer's disease and Frontotemporal Dementia (see Jagust et al. (2004), Neuro Rx, 1: 206-212, Matsuda (2007), J Nucl Med 48:1289-1300). However, differential diagnosis of Alzheimer's disease versus Lewy-Body Dementia currently requires an additional SPECT analysis, meaning that a differential diagnosis for Alzheimer's disease, Lewy-body Dementia, and Frontotemporal Dementia currently requires different PET and SPECT sessions.
Thus there is a continuing need for efficient methods that allow for differential diagnosis of degenerative types of dementia.